First of all, the good bits about the drill. It is powerful, fairly light and works a treat under light use so I can see why other customers give this a good review. Also the keyless chuck tightening/locking mechanism is good when it works (no need for a chuck key) and is a strong selling point.
Now the bad points. After a day of reasonably heavy duty use where I was drilling large holes in concrete blocks using hammer action selection, I discovered that on occasions the drill bit slips in the chuck. On this one occasion, drill bit slipped, the chuck tightened and duly jammed in a fixed position so that the chuck was no longer able to take any other drill bits. Most frustrating! Later, I learned that this is a general problem with keyless chucks in general, not just this drill. As a consequence I decided to return the drill for a refund as it was within the 30 day period from the purchase date. I do not want to spend my time trying to release/unjam the chuck mechanism every time the drill bit slips which is quite a common occurrence! This problem could have been solved if keyless chucks included the teeth for a key when this is needed. If this had been done then I would not have had to return this Bosch electric drill for a refund.
So if you do decide to go for a electric drill, such as this one, with keyless chuck then beware of the pitfalls. It is not for me and I will go back to an "older" conventional electric drill with the chuck key provided.